Method of coating metal



Patented re. 2e, 12.

s'rras EDWIN RUSS IUIILBHIG, OF ORANGE, NEW JERSEY, ASSIGNOB- TO AMERICAN MACHINE & FGU'NDRY COMPANY, A CORPORATION 012 NEW JERSEY.

HE'IHOD'OF COATETG IHETAL.

No Drawing.

This invention relates to a method of coating metal.

In coating metal with lead by the hot dipping process already known, tin phos- 5 phide or phosphor-tin is added to the bath of molten lead from time to time during the coating process, in order to prepare the molten lead for adherence to the metal to be coated, the proportion of phosphor-tin being not over 3% of the bath. During this process the phosphorus disappears, while the tin remains in the bath of molten lead. The result is, that while sufiicient phosphorus is maintained in the bath of molten lead to cause itto adhere to the metal to be coated, yet the tin accumulates in said bath and the percentage of tin therein gradually increases. The presence of some tin is necessary in order to increase the solu- 'bility of the phosphorus in the lead, but too much of it is detrimental to the practice of the art. The main object of the present invention is the production of a new method whereby the advantages of the tin are retained, but the accumulation and disadvantages of the same are avoided.

In carrying the invention into effect, a bath of molten lead is first prepared. Then there is added to the molten lead a modicum of tin, approximately'3% having been found to be sufiicient for the purpose. This tin contains no phosphorus but acts upon the lead to increase its solubility of phosphorus. Then there is added to the molten lead thus prepared and from time to time during the coating process, a modicum of phosphor lead to prepare and maintain the molten lead in condition for adherence to the metal to be coated, lead instead of tin bein the 40 vehicle by means of which the phosp orus is introduced intothe bath, and the quantity of phosphorus inv the phosphor lead being approximately the same as the quantity of phosphorus in the phosphor-tin heretofore used. By the use of this method, the addition of the phosphorus from time to time Application filed October 19, 1926. SeriaIHo. 142,784.

does not involve any increase in the percentage of tin in the bath, and the quantity of phosphor lead is so smallthat there is .no appreciable increase in the percentage of lead in the bath. But since the phosphorus disappears during the coating process, it is necessary from time to time during said process to add other Very small quantities of phosphor lead in order to maintain the molten lead in condition for adherence to the metal to be coated. The metal to be coated is passed through the molten lead thus prepared andmaintained in condition for adherence thereto. I

What is claimed is: i

1. A method of coating metal, which consists in' preparing a bath of molten lead,

then melting tin only in the molten lead to increase its solubility of phosphorus,=then adding phosphor lead to the molten lead and tin at the beginning of and from time to time during the actual coating operation to prepare and to maintain it in uniform condition for adherence to the metal to be coated, and then passing the metal to be coated through the bath thus prepared and maintained. v

2. The series of steps in a method of coating metal, which consists in preparing a bath of molten lead, then melting tin only in the molten lead to increase its solubility of phosphorus, then adding phosphor lead to the molten lead and tin at the beginning of and from time to time during the actual coating operation to prepare and to maintain it in uniform condition for adherence to the metal to be coated.

3. The series of steps in a method of coating metal, which consists in preparing a bath of molten lead containing'tm only to increase its solubility of phosphorus, and thereafter adding phosphor lead to the molten lead and tin.

- In testimony whereof, I have signed my name to this specification.

EDWIN ROSS 'MILLRI G. 

